The present invention relates to bit errors, and more particularly, to estimating bit error positions in a data decoder.
Error correcting techniques for correcting bit errors in digital data are often used to improve the reliability of data transmission. These techniques attempt to accurately retrieve the data with lowest bit error rate (BER). For example, a scheme of coding data by using convolutional codes and performing maximum likelihood decoding by using Viterbi decoding has a high error correcting capability. However, certain data such as compressed video data may be especially sensitive to bit errors. Thus, data frames containing bit errors may be identified using techniques such as cyclic redundancy check. In some applications or protocols, such as Transmission Control Protocol (TCP), these data frames containing bit errors may be retransmitted. However in other applications or protocols, such as real-time streaming video or User Datagram Protocol (UDP), re-transmission of error frames may not be practical or supported.
Further, when a frame of data such as video data known to contain errors is decoded for display, data recovery and/or error concealment techniques may be employed to mitigate visual distortions or artifacts caused by the errors. However if the position of bit errors within the frame cannot be estimated, substantially all or most of the error frame data, including both corrupted and uncorrupted data, may have to be discarded. Therefore, data recovery and/or error concealment techniques may be made substantially less practical when even the uncorrupted data is discarded.